Auto scanning of Collection

Hi All.
The last 5 or 6 times that I have used Volumio I have found that after a few minutes a message comes up telling me that my music collection is being scanned and not to use the player until it has finished. The message says to watch the rotating arrow at the bottom of the screen to check when the scan has finished, but there is no rotating arrow.
Any idea why an auto-scan is being performed each time I use Volumio?